题目链接
解题思路
- 由于所有边集中的边加起来的总和至多为
，无向图即
，可以存下
- 所以直接对所有边集中的边进行建边，同时对于每条边，记录其所在边集号
- 对于每个边集，由大到小维护其能通过的时间点
- 然后从1号跑最短路
- 到当前点
的时间为
，走边集
中的
这条边
- 则找边集
import java.io.*;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.BitSet;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.Map;
import java.util.Objects;
import java.util.PriorityQueue;
import java.util.Queue;
import java.util.Random;
import java.util.Stack;
import java.util.StringTokenizer;
import java.util.Vector;public class Main{static long md=(long)998244353;static long Linf=Long.MAX_VALUE/2;static int inf=Integer.MAX_VALUE/2;staticclass Node{int x,y;public Node(int u,int v) {x=u;y=v;}@Overridepublic boolean equals(Object o) {if(this==o)return true;if(o==null||getClass()!=o.getClass())return false;Node may=(Node)o;return x==may.x&&y==may.y;}@Overridepublic int hashCode() {return Objects.hash(x,y);}}staticclass Ti{Vector<Integer> tim;public Ti() {tim=new Vector<Integer>();}}staticclass Edge{int fr,to,val,nxt;public Edge(int u,int v,int w) {fr=u;to=v;val=w;}}static Edge[] e;static int[] head;static int cnt=0;static void addEdge(int fr,int to,int val) {cnt++;e[cnt]=new Edge(fr, to, val);e[cnt].nxt=head[fr];head[fr]=cnt;}public static void main(String[] args) throws IOException{AReader input=new AReader();PrintWriter out = new PrintWriter(new OutputStreamWriter(System.out));int n=input.nextInt();int t=input.nextInt();e=new Edge[400001];head=new int[n+1];cnt=0;for(int i=1;i<=t;++i) {int m=input.nextInt();for(int j=1;j<=m;++j) {int u=input.nextInt();int v=input.nextInt();addEdge(u, v, i);addEdge(v, u, i);}}Ti[] Dset=new Ti[t+1];for(int i=1;i<=t;++i)Dset[i]=new Ti();int k=input.nextInt();for(int i=1;i<=k;++i) {int x=input.nextInt();Dset[x].tim.add(i);}long[] dis=new long[n+1];Arrays.fill(dis, Linf);boolean[] vis=new boolean[n+1];dis[1]=0;PriorityQueue<Node> q=new PriorityQueue<Node>((o1,o2)->{return o1.y-o2.y;});q.add(new Node(1, 0));while(!q.isEmpty()) {Node now=q.peek();q.poll();int x=now.x;if(vis[x])continue;vis[x]=true;for(int i=head[x];i>0;i=e[i].nxt) {int v=e[i].to;int di=e[i].val;Vector<Integer> np=Dset[di].tim;int l=0,r=np.size()-1;int mi=inf;while(l<=r) {int mid=(l+r)>>1;int ti=np.get(mid);if(ti>dis[x]) {mi=ti;r=mid-1;}else l=mid+1;}if(mi==inf)continue;if(mi<dis[v]) {dis[v]=mi;q.add(new Node(v, mi));}}}if(dis[n]==Linf)out.print("-1");else out.print(dis[n]);out.flush();out.close();}//System.out.println();//out.println();staticclass AReader{ BufferedReader bf;StringTokenizer st;BufferedWriter bw;public AReader(){bf=new BufferedReader(new InputStreamReader(System.in));st=new StringTokenizer("");bw=new BufferedWriter(new OutputStreamWriter(System.out));}public String nextLine() throws IOException{return bf.readLine();}public String next() throws IOException{while(!st.hasMoreTokens()){st=new StringTokenizer(bf.readLine());}return st.nextToken();}public char nextChar() throws IOException{//确定下一个token只有一个字符的时候再用return next().charAt(0);}public int nextInt() throws IOException{return Integer.parseInt(next());}public long nextLong() throws IOException{return Long.parseLong(next());}public double nextDouble() throws IOException{return Double.parseDouble(next());}public float nextFloat() throws IOException{return Float.parseFloat(next());}public byte nextByte() throws IOException{return Byte.parseByte(next());}public short nextShort() throws IOException{return Short.parseShort(next());}public BigInteger nextBigInteger() throws IOException{return new BigInteger(next());}public void println() throws IOException {bw.newLine();}public void println(int[] arr) throws IOException{for (int value : arr) {bw.write(value + " ");}println();}public void println(int l, int r, int[] arr) throws IOException{for (int i = l; i <= r; i ++) {bw.write(arr[i] + " ");}println();}public void println(int a) throws IOException{bw.write(String.valueOf(a));bw.newLine();}public void print(int a) throws IOException{bw.write(String.valueOf(a));}public void println(String a) throws IOException{bw.write(a);bw.newLine();}public void print(String a) throws IOException{bw.write(a);}public void println(long a) throws IOException{bw.write(String.valueOf(a));bw.newLine();}public void print(long a) throws IOException{bw.write(String.valueOf(a));}public void println(double a) throws IOException{bw.write(String.valueOf(a));bw.newLine();}public void print(double a) throws IOException{bw.write(String.valueOf(a));}public void print(char a) throws IOException{bw.write(String.valueOf(a));}public void println(char a) throws IOException{bw.write(String.valueOf(a));bw.newLine();}}
}
